// 注意：你进行数据获取的方式取决于
// 你与 Suspense 集成的框架。
// 通常，缓存逻辑会在框架内部。

let cache = new Map();

function fetchData(url) {
  if (!cache.has(url)) {
    cache.set(url, getData(url));
    console.log('123')
  }
  console.log(cache.get(url))
  return cache.get(url);
}

async function getData(url) {
  if (url === '/the-beatles/albums') {
    return await getAlbums();
  } else {
    throw Error('Not implemented');
  }
}

async function getAlbums() {
  // 添加一个假的延迟，以便让等待更加明显。
  await new Promise(resolve => {
    setTimeout(resolve, 3000);
  });

  return [{
    id: 13,
    title: 'Let It Be',
    year: 1970
  }, {
    id: 12,
    title: 'Abbey Road',
    year: 1969
  }, {
    id: 11,
    title: 'Yellow Submarine',
    year: 1969
  }, {
    id: 10,
    title: 'The Beatles',
    year: 1968
  }, {
    id: 9,
    title: 'Magical Mystery Tour',
    year: 1967
  }, {
    id: 8,
    title: 'Sgt. Pepper\'s Lonely Hearts Club Band',
    year: 1967
  }, {
    id: 7,
    title: 'Revolver',
    year: 1966
  }, {
    id: 6,
    title: 'Rubber Soul',
    year: 1965
  }, {
    id: 5,
    title: 'Help!',
    year: 1965
  }, {
    id: 4,
    title: 'Beatles For Sale',
    year: 1964
  }, {
    id: 3,
    title: 'A Hard Day\'s Night',
    year: 1964
  }, {
    id: 2,
    title: 'With The Beatles',
    year: 1963
  }, {
    id: 1,
    title: 'Please Please Me',
    year: 1963
  }];
}

console.log(fetchData('/the-beatles/albums'))